Cell phone tracking system reveals how traffic jams start

Smartphones have changed the way we drive, both by adding new distractions and by helping us get where we're going with GPS-assisted directions and real-time information on traffic jams.

But what if smartphones could help eliminate some traffic jams, instead of just warning us when they exist? That's the goal of a study using cell phone records and GPS data to track drivers' movements and identify the sources of traffic.

The Boston Globe described the study today, noting that MIT and UC-Berkeley analyzed the cell phone records of 680,000 Boston-area commuters through call logs, "which identify the towers used to transmit calls," allowing "the researchers to trace each individual’s commute, anonymously, from origin to destination." This helped produce "one of the most detailed maps of urban traffic patterns ever constructed."

Boston-area roads. Red areas are the biggest sources of drivers. Yellow is next, then green, dark blue, and purple.

The study was published in December in the journal Scientific Reports, and described in announcements by MIT and Berkeley. Such cell phone tracking helps bring traffic analysis patterns into the modern age, with statistics being constantly updated instead of becoming constantly outdated.

"This is the first large-scale traffic study to track travel using anonymous cellphone data rather than survey data or information obtained from U.S. Census Bureau travel diaries," Berkeley's announcement said. Studies chronicled traffic both in Boston and San Francisco.

In Boston, it turned out traffic jams are caused by just a few drivers in the grand scheme of things, the Globe noted. "What they found, perhaps surprisingly, is that during rush hour, 98 percent of roads in the Boston area were in fact below traffic capacity, while just 2 percent of roads had more cars on them than they could handle," the Globe wrote. "The backups on these roads ripple outward, causing traffic to snarl across the Hub."

Moreover, "By tracking the cell records, they found that it’s just a small number of drivers from a small number of neighborhoods who are responsible for tying up the key roads. Specifically, they identified 15 census tracts (out of the 750 in Greater Boston) located in Everett, Marlborough, Lawrence, Lowell, and Waltham as the heart of the problem, because drivers from those areas make particularly intensive use of the problematic roads in the system."

This data doesn't offer any overnight solution to traffic congestion, but it may help city planners and public transportation officials better target their resources. Focusing on problem neighborhoods might be the key.

As MIT described, the adoption of alternatives like public transportation, carpooling, flex time, and working from home can be effective in reducing traffic if undertaken by a small number of people in certain problem areas.

The study demonstrated that "canceling or delaying the trips of 1 percent of all drivers across a road network would reduce delays caused by congestion by only about 3 percent," MIT wrote. " But canceling the trips of 1 percent of drivers from carefully selected neighborhoods would reduce the extra travel time for all other drivers in a metropolitan area by as much as 18 percent."

The effectiveness of this "selective strategy" is attributed in the study to the facts that "only [a] few road segments are congested" and that these road segments are clogged by people originating largely from only a few areas. Even though data was anonymous, researchers were able to infer drivers' home neighborhoods "from the regularity of the route traveled and from the locations of cell towers that handled calls made between 9 p.m. and 6 a.m," UC-Berkeley said.

Boston and San Francisco have "radically different commute patterns," UC-Berkeley noted. "In Boston, the freeways spread radially outward to the suburbs, with concentric rings of freeways intersecting them like a spider web. In San Francisco, the freeways encircle San Francisco Bay and are connected by six bridges."

Yet the key takeaway, that changing the habits of a very small group of drivers in certain areas is the most effective method of reducing traffic, remained the same in both Boston and San Francisco.

Since only three types of data—population density, topological information about road networks, and cell phone data—are needed, the same study could be repeated in almost any urban area.

A similar study was conducted in Copenhagen last year, also using cellular data. While the results were different (possibly because Copenhagen is such a small city compared to the US cities mentioned here) it is an easy and efficient method for traffic analysis. I am sure it is here to stay.

In fact I can see the telcos going into the data-mining business with this sort if thing, in order to make a profit. Surely the method can be adapted to analyze patterns for smaller locations as well - like the local mall, school, airport, etc.

(The ethics of it are another matter - I am speaking strictly about the technological potential)

Boston and San Francisco have "radically different commute patterns," UC-Berkeley noted.

I'll say. In Boston, the streets and signs are so nonlinear that every intersection becomes a value-judgement.

(I'm a Boston native, now living in the predictable street-grid of San Francisco. At least the topology is challenging, though.)

As a lifelong Massachusetts resident and former Boston resident, I'd say the Boston road system (when viewed from above) looks as though it was designed by a bunch of drunks in the Fenway bleachers between innings.

"the researchers to trace each individual’s commute, anonymously, from origin to destination."

Would have thought that by now people would learn that just because names or account numbers are removed from tracking data doesn't make it anonymous, more so when you are specifically tracking people leaving their house and arriving at work.

What else helps stop traffic jams? Leave room between you and the people in front of you, and pay attention to them. If they slow down, let off the gas, don't wait until the last minute & slam on the brakes. Hard braking sets up a standing wave from your car to all the other cars behind you.

What else helps stop traffic jams? Leave room between you and the people in front of you, and pay attention to them.

Unfortunately, in some cities (*ahem* possibly named in this article), leaving too much space between you and the car in front only results in a new car in front, filling the gap. It almost becomes a Zeno's Paradox of following distance.

What else helps stop traffic jams? Leave room between you and the people in front of you, and pay attention to them. If they slow down, let off the gas, don't wait until the last minute & slam on the brakes. Hard braking sets up a standing wave from your car to all the other cars behind you.

If you're an AV geek, think of it as being a low-pass filter.

Agreed. But have you tried it in Boston? For some reason people desperately covet the fifteen feet or less you leave between your car and the car in front of you. People lose their mind when driving.

Bypasses are devices which allow some people to drive from point A to point B very fast whilst other people dash from point B to point A very fast. People living at point C, being a point directly in between, are often given to wonder what's so great about point A that so many people of point B are so keen to get there, and what's so great about point B that so many people of point A are so keen to get there. They often wish that people would just once and for all work out where the hell they wanted to be.

Boston and San Francisco have "radically different commute patterns," UC-Berkeley noted.

I'll say. In Boston, the streets and signs are so nonlinear that every intersection becomes a value-judgement.

(I'm a Boston native, now living in the predictable street-grid of San Francisco. At least the topology is challenging, though.)

As a lifelong Massachusetts resident and former Boston resident, I'd say the Boston road system (when viewed from above) looks as though it was designed by a bunch of drunks in the Fenway bleachers between innings.

Certain parts of Boston have convoluted roads, but once you get used to the routes, it really isn't that difficult to navigate.

I've lived in plenty of places that have confusing street layouts. You get used to it. Pure grids aren't necessarily more efficient.

As a lifelong Massachusetts resident and former Boston resident, I'd say the Boston road system (when viewed from above) looks as though it was designed by a bunch of drunks in the Fenway bleachers between innings.

Herds of cows being brought to and from the Common is the traditional explanation.

Here's how to improve traffic in Boston: use cell towers to fine people for calling from a moving vehicle.

1.) It's not illegal to make a call as a passenger in a car.2.) It's not illegal to make a call as a driver either in many jurisdictions, as long as you are using a hands-free kit.

Personally, I find most traffic around here to be caused by another kind of idiot... Those that don't know how to merge. Several times, I've been behind someone that comes to a complete stop at a merge, including on the freeway. Usually it's the guy on the on-ramp slows down to pull in behind somebody. Guy on freeway slows down to let guy on ramp go in front, other guys slows down more, and so on. Next thing you know, both fools are completely stopped in the middle of the freeway, while traffic swerves around them.

If more people learned how to do a zipper merge, things would flow more easily. I hate when people just stop in the middle of the freeway, to merge over 2 miles ahead of time... And I hate the guy that doesn't like when others wait to merge until the actual merge, and purposely drive on the line to *BLOCK* people from legally using the right lane. Which is why I like how some cities have signs that say, "Use all lanes until lane actually ends"

My conjecture, which seems to have been lost, was that if people are paying attention to the road instead of their phones, then this will lead to better traffic.

If they aren't distracted by their phone, they will just be distracted by something else... After all, traffic has been bad before cell phones were so proliferated in society. Stupid people will just be stupid people, regardless what is in their hands... I've seen people read books while driving, shaving while driving, putting on makeup etc...

I live in Boston. Our roads are insane. I have a friend that lives on a street that is two way and, half way down the street it turns into a one way going the opposite direction. Basically, if you drive down that street expecting to get to other end of it, you just run into a one way and a big old ONE WAY DO NOT ENTER sign. You have to turn around in someone's driveway.

I live a couple of miles from a major highway in Boston. Occasionally a tourist will looked confused and ask for directions. I physically can't explain how to get there from here. It involves too many one way streets, strange merges and splits, and twisting half turns. I generally resort to just pulling open my phone, showing them the way, and feeling bad for them when that look of despair crosses their face. Their destination is only a couple of miles away, but good luck getting there.

Personally, I think the answer is autonomous cars. Once we get that shit figured out and fully street legal, the capacity of all of our roads is going to double a few times over. When we finally automate all non-recreational driving, I have a feeling that we will be able to tear up a non-trivial portion of our infrastructure and cities will come alive again with more walking space. Just the capacity to dump people off and then have the car find a parking lot underground would be a huge boon to eliminating congestion.

I didn't say it wasn't a distraction... I was just saying that you can't just fine somebody for it, unless it was illegal, which it isn't.

States could always tax it, like other "vices" that can't or shouldn't be outright banned. Make it perfectly legal to make cell calls in a moving vehicle with a hands-free device, but legislate that the cell carriers collect a tax, perhaps ten cents a minute. Find a way to know with reasonable certainty that an in-use phone is traveling over a given speed (I don't know the limitations of cell tower tracking). Dump the revenue into the state DoT as a way to help offset declining gas tax revenue.

If it's a tax to raise revenue and not a crime, the fact that one can't distinguish between drivers and passengers is no longer germane.

Personally, I think the answer is autonomous cars. Once we get that shit figured out and fully street legal, the capacity of all of our roads is going to double a few times over. When we finally automate all non-recreational driving, I have a feeling that we will be able to tear up a non-trivial portion of our infrastructure and cities will come alive again with more walking space. Just the capacity to dump people off and then have the car find a parking lot underground would be a huge boon to eliminating congestion.

Also taxis can function as affordable transit, since you remove the single most expensive part: The driver.

And if most people are willing to share taxis with strangers you'll double capacity again, and massively reduce parking needs. I'm not sure how many people would be willing to do that though.

I didn't say it wasn't a distraction... I was just saying that you can't just fine somebody for it, unless it was illegal, which it isn't.

It should be (and it is where I live, incidentally).

Change the law, fine people for making calls (need to work on the passenger issue -- presumably we can track phones accurately enough to work out how many are in a car? If all phones are used in a car, fine somebody, anybody!), give it a 12 month trial, see what happens.

Personally, I think the answer is autonomous cars. Once we get that shit figured out and fully street legal, the capacity of all of our roads is going to double a few times over. When we finally automate all non-recreational driving, I have a feeling that we will be able to tear up a non-trivial portion of our infrastructure and cities will come alive again with more walking space. Just the capacity to dump people off and then have the car find a parking lot underground would be a huge boon to eliminating congestion.

Also taxis can function as affordable transit, since you remove the single most expensive part: The driver.

And if most people are willing to share taxis with strangers you'll double capacity again, and massively reduce parking needs. I'm not sure how many people would be willing to do that though.

If I could dump my car and snap my fingers to make a car appear that I don't have to drive whenever I need it for less than the cost of owning a car, I wouldn't think twice. Some people love their cars, no doubt and will resist for years. People also used to love their horses. Some people still do, but they are a minority. As someone who lives in a city and loathes to drive, hates having to find parking, and would kill for the ability to sleep/eat/read on my way to work, I would happily shell out what I pay for a car now for the ability to not have to deal with a freaking car.

Cities would bloom with this. Imagine custom adhoc bus routs that appear in response to demand for people who are cheap, vans that you share with a couple of people for people who are less cheap, and private cars that take just you for those who have a time crunch or want privacy... and all this for less than the cost of a car. A car becomes a might cheap thing if instead of it rotting for 97% of its lifespan it is chasing fairs, paying for itself, and bringing back a little profit.

Personally, I think the answer is autonomous cars. Once we get that shit figured out and fully street legal, the capacity of all of our roads is going to double a few times over. When we finally automate all non-recreational driving, I have a feeling that we will be able to tear up a non-trivial portion of our infrastructure and cities will come alive again with more walking space. Just the capacity to dump people off and then have the car find a parking lot underground would be a huge boon to eliminating congestion.

Also taxis can function as affordable transit, since you remove the single most expensive part: The driver.

And if most people are willing to share taxis with strangers you'll double capacity again, and massively reduce parking needs. I'm not sure how many people would be willing to do that though.

I think I'd be less comfortable sharing a taxi without a driver than I would be sharing a taxi with one. Something about the lack of a visible witness makes me uneasy with the idea of trapping myself in a small moving metal box with a complete stranger.

I didn't say it wasn't a distraction... I was just saying that you can't just fine somebody for it, unless it was illegal, which it isn't.

States could always tax it, like other "vices" that can't or shouldn't be outright banned. Make it perfectly legal to make cell calls in a moving vehicle with a hands-free device, but legislate that the cell carriers collect a tax, perhaps ten cents a minute. Find a way to know with reasonable certainty that an in-use phone is traveling over a given speed (I don't know the limitations of cell tower tracking). Dump the revenue into the state DoT as a way to help offset declining gas tax revenue.

If it's a tax to raise revenue and not a crime, the fact that one can't distinguish between drivers and passengers is no longer germane.

it does offer a solution. Pay drivers a premium via their cell phone accounts to not drive on those congested roads.

A radio alert system could be created to give drivers in those areas advice on how to avoid the congested areas.

As a draconian statist suckstobeyou measure, we could close on-ramps from the most congestion-generating areas or limit traffic rates from those areas to roads where they are sure to generate backups for others.